Tin titanium zinc oxide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Experimental Toxicology and Ecology, BASF SE

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

485-430-0

EC Name:

-

Cas Number:

923954-49-8

Molecular formula:

SnxZnyTi2Oz with x = 0,5 – 1,7 y = 0,5 – 1,7 z = 5,5 – 7,5

IUPAC Name:

oxygen titanium zinc λ²-stannane

Details on test material:

- Test substance No.: 07/0285-1
- Substance type: solid, orange
- Analytical purity: 99.61 g/100 g (see analytical report, study code 07L00144):
- Lot/batch No.: GV 33900-66
- Storage condition of test material: room temperature

Method

Target gene:

not applicable

Species / strain

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Details on mammalian cell type (if applicable):

- Type and identity of media: MEM (minimal essential medium with Earle's salts) containing a L-glutamine source supplemented with 10% (v/v) fetal calf serum (FCS), 1% (v/v) penicillin/streptomycin (10 000 IU / 10 000 μg/mL), 1% (v/v) amphotericin B (250 μg/mL). During exposure to the test substance (only 4-hour treatment), MEM medium was used without FCS supplementation.
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes
- Periodically "cleansed" against high spontaneous background: yes

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced rat liver S-9 mix

Test concentrations with justification for top dose:

0.5, 1, 2, 4, 8 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO; 1% (v/v)
- Justification for choice of solvent/vehicle: Due to the insolubility of the test substance in the commonly used solvents, a homogeneous dispersion in DMSO was used in this study. It had been demonstrated that the vehicle DMSO is suitable in several mutagenicity test methods including the V79 in vitro cytogenetic test and for which historical control data are available.

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

Without metabolic activation Migrated to IUCLID6: 500 μg/ml dissolved in MEM without FCS (2.5 mg/mL)

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

With metabolic activation Migrated to IUCLID6: 0.5 μg/ml dissolved in MEM without FCS (2.5 μg/mL)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 4, 18 h
- Expression time (cells in growth medium): 10, 14, 24 h
- Fixation time (start of exposure up to fixation or harvest of cells): 2 - 3 hours

SPINDLE INHIBITOR (cytogenetic assays): 100 μL colcemid
STAIN (for cytogenetic assays): 7.5% (v/v) Giemsa/Titrisol solution pH 7.2 for 10 minutes.


NUMBER OF REPLICATIONS:
- experiment 1: 4h exposure, 18h sampling time, with and without metabolic activation
- experiment 2: 18h exposure, 18h sampling time, without metabolic activation; 18 h exposure, 28 hours sampling time, without metabolic activation; 4 hours exposure, 28 hours sampling time, with metabolic activation

NUMBER OF CELLS EVALUATED: 100 consecutive well-spread metaphases of each culture were counted for all test groups


DETERMINATION OF CYTOTOXICITY
- Method: mitotic index (1 000 cells, incl. mitotic cells, were counted per culture)

Evaluation criteria:

As a rule, the first 100 consecutive well-spread metaphases of each culture were counted for all test groups, and if cells had 20 - 22 chromosomes, they were analyzed for structural chromosome aberrations. In the case of clearly increased aberration rates, the number of metaphases to be analyzed for this test group can be reduced to at least 50 metaphases per culture.
In addition, numerical chromosome aberrations were scored and recorded.

Statistics:

The statistical evaluation of the data was carried out using the MUCHAN program system (BASF SE). The proportion of metaphases with structural aberrations was calculated for each group. A comparison of each dose group with the negative control group was carried out using Fisher's exact test for the hypothesis of equal proportions. This test was Bonferroni-Holm corrected versus the dose groups separately for each time and was performed one-sided. If the results of this test were statistically significant compared with the respective negative control, labels are printed in the tables.

Results and discussion

Test results

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: was not influenced by test substance treatment
- Effects of osmolality: was not influenced by test substance treatment


RANGE-FINDING/SCREENING STUDIES:
In the pretests for toxicity 5 000 μg/mL test substance was used as top concentration. The cells were prepared at a sampling time of 18 hours (about 1.5-fold cell cycle time) after 4 and 18 hours exposure time without S9 mix and after 4 hours exposure time with S9 mix.
The pretests were performed following the method described for the main experiment. As indication of test substance toxicity mitotic index, cell count, cell attachment (morphology) and quality of the slides were determined for dose selection.
In the pretests the parameters pH value and osmolarity were not relevant influenced by the addition of the test substance preparation to the culture medium at the concentrations measured.
Regarding the toxicity of the test substance reduced cell numbers of below 50% of control were observed at 5 000 μg/mL after 4 hours treatment in the absence of S9 mix only. No cytotoxicity occurred after 4 hours treatment in the presence of S9 mix or after 18 hours treatment in the absence of S9 mix.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Mitotic index: In the main experiments, according to the results of the determination of the mitotic index, no suppression of the mitotic activity was observed under all experimental conditions up to the highest applied concentration in the absence and presence of S9 mix.
- Cell counts: According to the results of the determination of the cell count in the main experiments, no growth inhibition was observed under all experimental conditions up to the highest applied concentration in the absence and presence of S9 mix.
- Cell morphology: Cell attachment was not influenced at any dose evaluated for structural chromosomal aberrations in the absence and presence of S9 mix.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Results:

			Genotoxicity				Cytotoxicity
Schedule	Test group	S-9 mix	aberrant cells (%)			polyploid cells (%)
Exposure/Preparation period			incl gaps	excl. Gaps	with exchanges		Cell number (%)	Mitotic index (%)
4/18 h	vehicle	-	3.5	1.5	1	2	100	100
	0.5 µg/ml	-	-	-	-	-	101.1	-
	1 µg/ml	-	9.5s	2	1	0.5	121.3	124.9
	2 µg/ml	-	9.5s	5	2	2	105.2	104
	4 µg/ml	-	6	2	1	1	98.3	109
	8 µg/ml	-	-	-	-	-	110.9	-
	EMS	-	22.0s	20.0s	11s	0		105.1
18/18 h	vehicle	-	5	2.5	0.5	0.5	100	100
	0.5 µg/ml	-	-	-	-	-	108.5	-
	1 µg/ml	-	6	2	1	0.5	110	110.3
	2 µg/ml	-	6	2	1.5	0	116.6	119.3
	4 µg/ml	-	6	3	1.5	0.5	117.5	104.1
	8 µg/ml	-	-	-	-	-	104.7	-
	EMS	-	29.0s	24.0s	15.0s	0		81.4
18/28 h	vehicle	-	4.5	3	0.5	0.5	100	100
	2 µg/ml	-	-	-	-	-	100.6	-
	4 µg/ml	-	5	4	2.5	0	83.1	101.4
	8 µg/ml	-	-	-	-	-	73.9	-
	EMS		23.0s	22.0s	19.0s	0		90.8
4/18 h	vehicle	+	7.5	1.5	0.5	1.9	100	100
	0.5 µg/ml	+	-	-	-	-	80.8	-
	1 µg/ml	+	8.5	2.5	1	2.9	81.2	90.4
	2 µg/ml	+	11.5	3.5	1.5	3.4	76.6	105.7
	4 µg/ml	+	9	3	2	1.9	79.5	79.7
	8 µg/ml	+	-	-	-	-	83.3	-
	CPP	+	22.0s	19.0s	14.0s	0		81.2
4/28 h	vehicle	+	9.5	4	1	0.5	100	100
	0.5 µg/ml	+	-	-	-	-	11.6	-
	1 µg/ml	+	3.5	1	0.5	1.5	114.9	115.9
	2 µg/ml	+	3	2.5	0	0.5	101.8	1117.7
	4 µg/ml	+	8.5	1	0	1	103.5	86.8
	8 µg/ml	+	-	-	-	-	111.4	-
	CPP	+	15	15.0s	9.0s	1		129.1

s: aberration frequency statistically significant higher than corresponding control values